Spark-plug.



W. S` THOMA",

SPARK mi APPLECATIO MH. 4, 19H? WILLIAM S. THOMAS, OF LOCK HAVEN, PENNSYLVANIA.

SPARK-PLUG.

Specification of Letters Patent.

'Patented Dec.. 752i?, Nitti.

Application tiled January 1918. Serial No. 210.252.

kTo aZZ-ww/n it may concern .Be it known that i, WILLXAM t-. talents` a citizen of the United States, residing at Lock Haven, in the county oi Clint-on and State et' Pennsylvania, have .invented certain new and useful Improvements in Spark- Plugs, ol which the following lev a specitication.

My invention relates to spark plugs such as used in connection with internal combustion engines and consists particularly of auxiliary elect-rode insulating means which 1s so located and positioned as to prevent eil, gas, or the products olf comlnistion in the engine i'rom penetrating said insulating means, thereby increasing` the eliicie'ncy ot the plug, thus reducing the, loss oiE electrical current to a minimum through insulator leakage.

A further object is to construct and so arrange my invention that a spark plug made in accordata-e therewith will ne durable under the severe, conditions encountered in regular use.

Another object is to`so construct my iinprovcd spark plug that the auxiliary insulator will act as a resilient cushion between a jacket which l employ and the primary insulator for om` of the electrodes.

still further object of my invention is to so arrange said auxiliaryv insulator that it will keep the primary insulator' con1para tively cool. Y

Another object of my invention is to provide auxiliaryinsulating means which can be used in tight connection with a porcelain or glass insulator for a ren'iovable electrode, without breaking the glass or porcelain.

These objectshand other advantageous ends which will be described hereinafter. attain in the following manner, rc/lerence being had to the accompanying drawings in which- Figure l is an elevation, partly in section, showing a portion ot a spark plug made in accordamre with my invention7 Fig. 2 shows an elevation oi? a porcelain insulated electrode haring a hand ot mica thereon inadein accordance with my invention Fig. is a `tlansverse section taken on the line s-3 offFig; 1,

Fig. 4 is a sectional elevation oi" my improved mica band showing how the saine is made in two sections and separated from lach other, and

AFig. 5 is an elevation partly in section showingan entire spark plug made in accordance with my invention and ot' a (litterent form irom that shown in Fig. l.

ltet'erring to Figs. l to i, inclusive`r of the th'awings, l represents an electrode having a primary lnn'celain or glass insulator 2. This insulator has an enlarged portion 3 within its length. said enlarged portion having substantially [lat upper and lower surfaces 4' and i3, respectively. which provide substantially parallel shoulders to a purpose hereinafter described. n auxiliary insulating' band of nuca or other`iusulating material (3 is adapted to surround the enlarged portion Si and this band ot mica. l'orins one ot the important features ot this invention. The band (i is preferably made in two sections 7 and S. rlhe bottom section S has an inturned circular flange t) which is adapted to engage the shoulder and to surround the lower stem. portion 10 ot the insulator lhe upper portion ot the section S is reduced in diameter, as shown at ll, and a circular ledge or v shoulder l2 is thus provided. rl`he upper section T has a depending portion 13 which is o'l: a diameter lo'snugly tit. -the upper edge portion otE the section S and to abut the ledge l2 when the two sections are placed together. The section 7 also has an internal tlange l-i which is adapted to surround the upper stem portion l5 ot the insulator 2.

'lhe outer diameters ot' the sections 7 and S are substzmtially the same so that when they are placed together the outer surfaces will be (lush. 'lhe flange lrl-` is adapted to extend over and into engagement with the upper shoulder `loi.' the enlarged portion 3 ot the insulator Thus the enlarged portion 3 of the insulator is housed within the band of mica 6. f

The, band G is preterabl y made by cutting,r a block ot micav on a lathe or other machine and aft'terward this band is tightly fitted around the enlarged portion 3, in the inanuer as shown in Fig. 2. As illustrated in Figs. 'l and i, the insulator with the mica hand 6 is inclosed within a metallic jacket '1(3. This jacket includes uppe and lower [langes 17 and 1S, respectively, which are, turned and pressed inwardly by pressure dcvices not illustrated), and washers 19 and 2O are interposed between the flange 17 and the section .l of the mica band 6, and the iiange 18 and the bottom of the section 8 of said mica band 6. y

The jacket 16 forms an inclosure for the auxiliary insulating band 6 and serves as a seal to prevent direct contact of the products of combustion within the engine with the auxiliary band 6. jacket serves as a. protective means to prevent oil or carbon particles from engaging the auxiliary insulating band 6 and thereby renders the insulating properties ofthe band G extremely efficient since it is well known that if mica or similar material is impregnated with oil and carbon that it serves and acts as a conductor instead of an insulator for which it is intended.

The washer 20 is preferably made U-shape in cross section (see Fig. 1) and is preferably made of resilient metal so as to provide a tight lit between the several parts. This washer 20 is adapted-to engage the .bottom portion l0 of the insulator 2 and prevents any portion of the products of combustion, which may be passed between the inner 'edge of the flange 18 and the portion 10 of tho insulator 2, from engaging the auxiliary insulating` band 6. This washer 2O is preferably made of sufficiently flexible material which can firmly engage rthe insulator 2 without causing fracture or other injury thereto. An electrode thus housed can be placed within the body portions (not illustrated) of various types of spark plugs, such for example as the body portion of the spark plug illustrated in my application for United States patent, Serial No.17769.

In Fig. 5 I have illustrated the electrode insulator having the band 6 thereon and positioned directly within a body portion 2l of a spark plug, said body portion having a lower screw-threaded end 22 whichcan be screwed directly into an enginecylinder.

In this construction I have used flat wash-- ers 23 and 2li positioned between the top and bottom of the band 6 of the shoulder 25 of the body portion andv the top iangeV 26 of said body portion; In all other respects the construction is-"similar to that described in Figs. 1 to 4, inclusive, and I have, therefore, given similar parts corresponding reference numerals:

I preferably produceva tightit between the outer surface of themica band 6 and the inner surface lofthe inner jacket 16 or Furthermore, this l self to the precise construction set forth, but

consider that I am at liberty to make s'uch changes and alterations as fairly come within the scope of the appended claims.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

l. An electrode; an insulator l,for said electrode and having an enlarged portion within its length and providing top and bottom shoulders; an auxiliary band of insulating material surrounding said enlarged portion and having flanges embracing said shoulders; and a metallic jacket incasing the top, bottom and side of said band, substantially as described. j

2. An electrode; an insulator` for said electrode and having an enlarged portion within its length and providing top and bottom shoulders; an auxiliary band of insulating material surrounding said enlarged portion and having flanges embracing said shoulders, said band being made in sections havingJ interla'pping portions; and a metallic jacket incasing the top, bottom and side of said band, substantially as described.

3. An electrode; an insulator for said electrode and having an' enlarged portion within its'length and providing top and` bottom shoulders; an auxiliary band of insulating material surrounding said enlarged portion and having flanges embracing said shoulders; and a jacket surrounding the side of said band and having inwardly extending portions positioned above and below the ianges of said band, substantially as described.

Ll. An electrode; an insulator for said elec'- trode and having an enlarged portion within its length and providing top and bottom shoulders; an auxiliary band of insulating material surrounding said enlarged portion and having llanges embracing said shouldeis;I a jacket surrounding the side of said band and having inwardly extending portions positioned above and below the flanges of said band; and washers interposed between said inwardly. extending portions of said jacket and the flanges. of said band, substantially as described.

5. A spark plug of the character described `including an electrode; an insulator therefor; an auxiliary insulatingband of mica tightly surrounding said electrode insulator; and a metallic jacket tightly inclosing the top, bottom and side of said auxiliary band, si'xbstantially as described.

I testimony whereof I have signed my .Hilf-ll@ two subscribing witnesses.

WILLIAM Si THOMAS.

'Witnesses I MARY A. luenen, Claas. E. Porre.

to this specication in the presenceof aanstaan 

